Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=true, so safety is covered. The description usefully discloses what the response carries (status, double opt-in, custom fields) and the underlying GET endpoint, but says nothing about pagination bounds, rate limits, or result ordering.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Two dense sentences, front-loaded with the resource and the payload. The field enumeration is long but earns its place by telling the agent what comes back; the endpoint suffix is mildly redundant with the operation name.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a 10-parameter, nested-filter, read-only tool with no output schema, the description covers what is returned and how custom-field filtering works. Pagination (limit/offset/next_offset) is left entirely to the schema, which is a minor but real gap for a paged list operation.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 80%, so most parameters are already documented in the schema. The description's filter examples ({"city":"Brisbane"}, {"source:ne":"promo"}) largely restate the schema's own filters description, adding only the point that custom fields are targetable and that arbitrary fields are filterable; no extra semantics for limit/offset/fields.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb+resource ('List the contacts of one list') and enumerates the returned attributes, so it is clearly distinct from vision6_get_contact. It never names a sibling explicitly, so the boundary against vision6_list_sent_contacts or vision6_list_list_fields is left implicit.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Usage is implied by the endpoint ('GET /lists/{list_id}/contacts') and the filter examples show how to narrow results, but there is no explicit when-to-use guidance or statement of when a different sibling (e.g. vision6_list_sent_contacts or vision6_get_contact) is the better call.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.